/Engine/Source/Runtime/Slate/Public/Widgets/Input/SSubMenuHandler.h
The system will use this event to notify a widget that the cursor has entered it. This event is uses a custom bubble strategy.
virtual void OnMouseEnter ( const [FGeometry](API\Runtime\SlateCore\Layout\FGeometry) & MyGeometry, const [FPointerEvent](API\Runtime\SlateCore\Input\FPointerEvent) & MouseEvent )